Project Summary World Trade Center (WTC) first responders have suffered numerous diseases and conditions as a result of their efforts on 9/11 and afterwards. For example, it has been noted that there are numerous cases of aerodigestive disorders amongst the responders, including sinusitis, asthma, interstitial lung disease, and gastroesophageal reflux. Similarly, there are reports of higher than expected rates of certain cancers, such as multiple myeloma, prostate, and thyroid. Also reported are relatively high rates of post-traumatic stress disorder, anxiety, depression, and sleep apnea. The commonality in these reports is the comparator groups against which the data from the WTC General Responders Cohort (WTC-GRC) were measured. The comparator groups were either national or local (e.g., the NY State Cancer Registry) and were composed of members of the general population, not occupational groups. The purpose of this proposal is the development of a unique occupational cohort, based in part on patients attending the Mount Sinai Selikoff Centers for Occupational Health (SCOH), as well as workers presenting to other departments within Mount Sinai, and workers recruited through outreach efforts. The reasoning is that for valid estimates of the health of the first responders, comparisons must be against a working population and not the general population, which can lead to intractable bias and faulty assessments. The specific aims of the proposed project include: 1) converting existing SCOH data into a usable database for comparative analyses of WTC-related health conditions; 2) building a new occupational cohort to serve as a comparison in the longitudinal assessment of health in the WTC-GRC; and 3) utilizing the newly created comparison cohort to determine if gastroesophageal reflux disease (GERD) incidence in the WTC-GRC differs from an unexposed worker population. The results of the proposed project will improve the quality of the health related studies being done by providing a more appropriate comparison group that can be matched to responders on several important characteristics, including occupation, age, sex and race/ethnicity. Such studies will result in improved estimates of disease risk and add important knowledge to what we currently understand about exposure to 9/11 toxins and stressors.